Short-term reliability of inflammatory mediators and response to exercise in the heat |
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| Authors: | Joshua H Guy Andrew M Edwards Catherine M Miller Glen B Deakin David B Pyne |
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| Institution: | 1. Department of Sport and Exercise Science, James Cook University, Cairns, Australia;2. Faculty of Sport and Health Sciences, University of St Mark and St John, Plymouth, UK;3. College of Public Health, Medical and Veterinary Sciences, James Cook University, Cairns, Australia;4. Department of Physiology, Australian Institute of Sport, Canberra, Australia |
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| Abstract: | Prospective application of serum cytokines, lipopolysaccharide (LPS), and heat shock proteins (eHSPs) requires reliable measurement of these biomarkers that can signify exercise-induced heat stress in hot conditions. To accomplish this, both short-term (7 day) reliability (at rest, n = 12) and the acute responsiveness of each biomarker to exercise in the heat (pre and post 60-min cycling, 34.5°C and 70% RH, n = 20) were evaluated. Serum was analysed for the concentration of C-reactive protein (CRP), interleukin-6 (IL-6), heat shock protein 72 (eHSP72), immunoglobulin M (IgM) and LPS. Test–retest reliability was determined as the coefficient of variation (CV). Biomarkers with the least short-term within-participant variation were IL-6 (19%, ±20%; CV, ±95% confidence limits (CL)) and LPS (23%, ±13%). Greater variability was observed for IgM, eHSP72 and CRP (CV range 28–38%). IL-6 exhibited the largest increase in response to acute exercise (95%, ±11%, P = < 0.001) and although CRP had a modest CV (12%, ±7%), it increased substantially post-exercise (P = 0.02, ES; 0.78). In contrast, eHSP72 and LPS exhibited trivial changes post-exercise. It appears variation of common inflammatory markers after exercise in the heat is not always discernible from short-term (weekly) variation. |
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| Keywords: | Lipopolysaccharide heat shock proteins inflammatory cytokines heat tolerance |
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